How to fix misaligned and improperly referenced spatial data
The first step is to bring up ArcCatalog and preview the data information. This can be done by right clicking the layers, opening the properties, and scrolling down until you see the spatial reference section. When you have reached that section you are then able to compare the information.
For each file, observe the coordinate reference system. This can be found adjacent to the bold Spatial Reference header (Ex. GCS_North_American_1983). You are able to add the preferred layers onto the map by selecting the layer and dragging it from the ArcCatalog drop menu into the Table of Contents or you can also select the “add data” button on top of the tool bar.
Once you have assured all your layers that were selected are displayed on the map you can begin analysis. However, if you do notice files that having missing spatial references they may not show on the map.
Solution: Find out what coordinate system your layer is in and then apply that to the data for alignment. To do this you go to ArcCatalog then missing layer’s properties. You will see an XY coordinate tab and from there you will be able to see the coordinate system that you found matches your layer, you would apply it to the layer.
For further analysis, one can project different layers to make them into the same coordinate system. The coordinate system should depend on what analysis you are doing. When wanting to project and finalize a map, it is important to make sure that the layers are consistent with each other in terms of their coordinate systems. In order to fix misaligned or improperly referenced data, make sure to change the coordinate system to that of the base layer. The base layer should also be the most accurate layer. When the layers are in different coordinate systems, it could result in misinterpretations of the data and possibly inaccurate data obtained when calculating pieces of information like areas or distances.
Advantages of using remotely sensed Landsat data for geographic analysis
Remotely sensed Landsat data for geographical analysis are data sets that are collected by sensors on a satellite. The sensors record emitted and reflected energy through the wavelengths of the electromagnetic spectrum. Landsat data has contributed greatly in assisting water quality monitoring, monitoring of: glacier recession, sea ice movement, invasive species encroachment, coral reef health, land use change, deforestation rates and population growth. It is also a beneficial tool because it has helped assess damages from natural disasters: fires, floods, and tsunamis, and can subsequently, plan disaster relief and flood control programs. Landsat data also has its advantages because the images are always available in digitized form so that it is compatible with a computer. It more importantly allows us to survey and monitor regions that people may have difficulty accessing. An example would be if an earthquake were to happen around Mount St. Helens, we would be able to observe the changes that occurred.